Powerful + 6 Long Lasting Refill Rollers Included: Coarse and powered enough for automatic buff and nail shine polishing; Tested effective for thick toe nail filing. The Own Harmony toenail grinder features upgraded 2000 rpm built in battery so you can remove nail ridges or turn thick toenails into smooth, polished pedicure; Includes 6 refill rollers – 2 nail rollers for filing and buffing, 2 roller heads for nail shine polishing, 2 foot callus remover heads for dry, dead skin removal.